class Queue {
  constructor(val) {
    this.items = {};
    this.count = 0;
    this.first = 0;
  }
  enqueue(val) {
    this.items[this.count] = val;
    this.count++;
  }
  isEmpty() {
    return this.count - this.first === 0;
  }
}
let queue = new Queue();
queue.enqueue(1);
queue.enqueue("12");
console.log(queue);
console.log(queue.isEmpty());
